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Date: Tue, 16 Apr 2024 18:09:03 -0400
From: Kent Overstreet <kent.overstreet@linux.dev>
To: Nathan Chancellor <nathan@kernel.org>
Cc: bfoster@redhat.com, linux-bcachefs@vger.kernel.org, 
	linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH] bcachefs: Fix format specifier in validate_bset_keys()
Message-ID: <xznpzlnjcf3goexunm6azwercgwz7ikgum3i4gpdyxwykb4e4l@ascd3uztphq3>
References: <20240416-bcachefs-fix-format-specifier-validate_bset_keys-v1-1-3ea2cdf28b12@kernel.org>
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In-Reply-To: <20240416-bcachefs-fix-format-specifier-validate_bset_keys-v1-1-3ea2cdf28b12@kernel.org>

On Tue, Apr 16, 2024 at 08:16:02AM -0700, Nathan Chancellor wrote:
> When building for 32-bit platforms, for which size_t is 'unsigned int',
> there is a warning from a format string in validate_bset_keys():
> 
>   fs/bcachefs/btree_io.c: In function 'validate_bset_keys':
>   fs/bcachefs/btree_io.c:891:34: error: format '%lu' expects argument of type 'long unsigned int', but argument 12 has type 'unsigned int' [-Werror=format=]
>     891 |                                  "bad k->u64s %u (min %u max %lu)", k->u64s,
>         |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   fs/bcachefs/btree_io.c:603:32: note: in definition of macro 'btree_err'
>     603 |                                msg, ##__VA_ARGS__);                     \
>         |                                ^~~
>   fs/bcachefs/btree_io.c:887:21: note: in expansion of macro 'btree_err_on'
>     887 |                 if (btree_err_on(!bkeyp_u64s_valid(&b->format, k),
>         |                     ^~~~~~~~~~~~
>   fs/bcachefs/btree_io.c:891:64: note: format string is defined here
>     891 |                                  "bad k->u64s %u (min %u max %lu)", k->u64s,
>         |                                                              ~~^
>         |                                                                |
>         |                                                                long unsigned int
>         |                                                              %u
>   cc1: all warnings being treated as errors
> 
> BKEY_U64s is size_t so the entire expression is promoted to size_t. Use
> the '%zu' specifier so that there is no warning regardless of the width
> of size_t.
> 
> Fixes: 031ad9e7dbd1 ("bcachefs: Check for packed bkeys that are too big")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202404130747.wH6Dd23p-lkp@intel.com/
> Closes: https://lore.kernel.org/oe-kbuild-all/202404131536.HdAMBOVc-lkp@intel.com/
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Thanks, applied